A rigid thermal insulation felt and its preparation method

Abstract

This application discloses a rigid thermal insulation felt and its preparation method, comprising applying an impregnation composition to a carbon fiber felt to obtain an impregnated felt body; the impregnation composition includes silica, which adheres to the carbon fiber felt during the impregnation process; the impregnated felt body is subjected to carbonization and graphitization treatments, so that the silica in the impregnated felt body reacts with the carbon fibers in the carbon fiber felt to generate silicon carbide, obtaining felt body units; multiple felt body units are bonded together with an adhesive to obtain the rigid thermal insulation felt. The preparation method of this application is simple and has low production difficulty. Through carbonization and graphitization treatments, the silica adhering to the carbon fiber felt reacts with the carbon fibers at high temperature to generate silicon carbide, thereby synergistically improving the strength and thermal insulation performance of the rigid thermal insulation felt without significantly increasing its density, and extending its service life.

Description

Technical Field

[0001] This application relates to the field of thermal insulation materials technology, and in particular to a rigid thermal insulation felt and its preparation method. Background Technology

[0002] Rigid insulation felt is easy to shape and has good insulation performance. The surface layer is bonded with carbon cloth or graphite paper, which can prevent slag from falling and causing short circuits in high-temperature furnaces. Due to its excellent properties of being easy to process and install, it is becoming increasingly popular in the market. However, rigid insulation felt is mostly made of soft felt bonded together. The thickness is changed by controlling the number of control layers during installation. Due to the influence of the bonding strength, it is prone to interlayer cracking and peeling of the surface carbon cloth or graphite paper during use, and the insulation performance is also reduced.

[0003] In existing technologies, thermal insulation felt requires low density to achieve good thermal insulation performance, which also results in low strength. Increasing density can enhance the strength of the thermal insulation felt, but the thermal insulation performance will decrease. Therefore, it is difficult for existing products on the market to simultaneously guarantee strength and thermal insulation performance. Typically, the service life of these products is 8-12 months, which is relatively short. In addition, some processes use needle punching to prepare thermal insulation felt, but the needle punching process has high requirements, and the preparation process is difficult when the thermal insulation felt is thick. Summary of the Invention

[0004] To address the problems existing in the prior art, this application provides a rigid thermal insulation felt and its preparation method. The preparation process is simple and can simultaneously improve the strength and thermal insulation performance of the rigid thermal insulation felt, thereby extending its service life. The technical solution is as follows:

[0005] This application provides a method for preparing rigid thermal insulation felt, including:

[0006] S1, The impregnation composition is applied to the carbon fiber felt to obtain the impregnated felt body; the impregnation composition includes silica, which adheres to the carbon fiber felt during the impregnation process;

[0007] S2, the impregnated felt body is subjected to carbonization and graphitization treatment so that the silica in the impregnated felt body reacts with the carbon fibers in the carbon fiber felt to generate silicon carbide, thereby obtaining the felt body unit.

[0008] S3, multiple felt units are bonded together with an adhesive to obtain the rigid thermal insulation felt.

[0009] Furthermore, the impregnated felt body undergoing carbonization and graphitization treatment is a shaped impregnated felt body. Before step S2, the method further includes:

[0010] The impregnated felt is subjected to a shaping treatment at a pressure of 1-5 MPa and a temperature of 150-300°C to obtain a shaped impregnated felt.

[0011] Furthermore, the carbonization temperature is 800–1100°C, and the carbonization time is 4–8 hours;

[0012] The graphitization treatment temperature is 2000–2200℃, and the carbonization treatment time is 10–15 h.

[0013] Furthermore, the felt units in the process of bonding the multiple felt units together with an adhesive are activated felt units. Before step S3, the method further includes:

[0014] The surface of the felt unit is subjected to corona treatment to form activated functional groups on the surface of the felt unit, thereby obtaining an activated felt unit; the power of the corona treatment is 10-30kW, and the corona treatment time is 15-100s; during the bonding process, the activated functional groups can be connected to the adhesive through chemical bonds.

[0015] Furthermore, after bonding the plurality of felt units together with an adhesive, the method further includes:

[0016] The bonded activated felt units are hot-pressed at a temperature of 150–300°C to obtain the rigid thermal insulation felt.

[0017] Furthermore, the carbon fiber felt includes graphite felt, which includes one or more of viscose-based graphite felt, pitch-based graphite felt, and polyacrylonitrile-based graphite felt.

[0018] Furthermore, the impregnation composition satisfies at least one of the following characteristics:

[0019] The particle size of the silica is 4–20 μm;

[0020] The mass fraction of the silica in the impregnation composition is 1-5%;

[0021] The impregnation composition further includes a resin impregnation solution comprising resin, ethanol and a thickener, wherein the mass ratio of the resin to the ethanol is 1:(5-15), and the mass fraction of the thickener in the resin impregnation solution is 1-5%.

[0022] The resin includes one or more of phenolic resin, epoxy resin, acrylic resin and epoxy polyurethane;

[0023] The thickener includes one or more of polyvinyl alcohol fiber, carboxymethyl cellulose fiber, seaweed fiber, hydroxyethyl cellulose, methyl hydroxyethyl cellulose, ethyl hydroxyethyl cellulose and methyl hydroxypropyl cellulose.

[0024] Further, step S1 includes:

[0025] The impregnation composition is added to the carbon fiber felt multiple times by injection to obtain the impregnated felt body; the thickness of the carbon fiber felt is 5-15 mm, and the dosage of the impregnation composition added each time is 1-3 mL / cm. 3 The impregnation composition is added 3 to 8 times.

[0026] Furthermore, prior to step S2, the method further includes:

[0027] A sealing agent is applied to the surface of the impregnated felt to form a sealing layer on the surface of the impregnated felt, thereby obtaining a sealed impregnated felt; the sealing agent includes resin, ethanol and thickener, wherein the mass ratio of resin to ethanol is (1-5):1, and the mass fraction of thickener in the sealing agent is 5-12%.

[0028] This application also provides a rigid thermal insulation felt obtained by the preparation method described in any of the preceding claims.

[0029] Implementing this application will have the following beneficial effects:

[0030] 1. This application uses a precipitating composition containing precipitated silica to impregnate carbon fiber felt, and then performs carbonization and graphitization treatments before bonding to obtain rigid thermal insulation felt. The preparation method is simple and easy to operate. The precipitated silica adhering to the carbon fiber felt reacts with the carbon fiber after carbonization and graphitization treatments to generate silicon carbide. Without significantly increasing the density of the rigid thermal insulation felt, it synergistically improves the strength and thermal insulation performance of the rigid thermal insulation felt and extends its service life. Furthermore, this preparation method does not require multiple coating and drying of the felt unit, nor does it require the process of pasting graphite paper or carbonization on the surface of the finished rigid thermal insulation felt, which greatly simplifies the production process, reduces production difficulty, and helps to save production costs.

[0031] 2. Before bonding the felt units, this application first performs corona treatment on the surface of the felt units to form activated functional groups on the surface of the felt units. These activated functional groups can form interlayer connections with the adhesive through chemical bonds during the bonding process. The strength of chemical bonds is much stronger than that of physical bonding, which greatly improves the interlayer bonding force between the multilayer felt units, making it less prone to delamination and effectively avoiding interlayer cracking during long-term use. This preparation method is simple and takes into account the strength, thermal insulation performance and anti-interlayer cracking performance of rigid thermal insulation felt, greatly improving the performance of rigid thermal insulation felt and extending its service life. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in the embodiments will be briefly described below, wherein the same components are represented by the same reference numerals. Obviously, the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0033] Figure 1 A logic flowchart of a possible implementation of the rigid thermal insulation felt provided in this application;

[0034] Figure 2 A flowchart illustrating the shaping process in an optional embodiment of the preparation method of rigid thermal insulation felt provided in this application;

[0035] Figure 3 A logic flowchart illustrating the formation of a sealing layer in a method for preparing rigid thermal insulation felt in one optional embodiment of this application;

[0036] Figure 4 The diagram shows the logic flow of corona treatment in the preparation method of rigid thermal insulation felt in one optional embodiment of this application. Detailed Implementation

[0037] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments, and therefore should not be construed as limiting this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] It should be noted that the terms "first," "second," etc., used in the specification, claims, and drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described below. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or server that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

[0039] Existing rigid insulation felt technologies cannot simultaneously achieve both strength and insulation performance. Some manufacturing methods involve externally fixing high-strength boards, which, while increasing strength, makes interlayer cracking more likely. However, bolting to prevent interlayer cracking compromises the insulation and overall performance of the rigid insulation felt. Furthermore, adhesives are often used to bond thin felt raw materials together to form rigid insulation felt, but during use, the adhesives have a significant impact. As usage time increases, cracking easily occurs between multi-layer felt units, reducing the lifespan of the rigid insulation felt. Some manufacturing methods use needle punching to address delamination, but this requires high precision and is too difficult when the final thickness of the rigid insulation felt is large.

[0040] To address at least one of the aforementioned problems, this application provides a rigid thermal insulation felt and its preparation method, capable of producing a rigid thermal insulation felt that combines strength, thermal insulation performance, and anti-interlayer cracking performance, thereby extending the service life of the rigid thermal insulation felt. The preparation method is simple, including applying an impregnation composition containing precipitated silica to a carbon fiber felt, whereby the precipitated silica adheres to the carbon fiber felt during impregnation, resulting in an impregnated felt body; subsequently, the impregnated felt body undergoes carbonization and graphitization treatments, allowing the precipitated silica adhering to the impregnated felt body to react with the carbon fibers in the carbon fiber felt to generate silicon carbide, obtaining felt body units; finally, multiple felt body units are bonded together using an adhesive to obtain a rigid thermal insulation felt. During the preparation process, silica and carbon fiber react at high temperature to generate silicon carbide. The introduction of silicon carbide does not increase the density of the felt unit, ensuring the thermal insulation performance of the rigid insulation felt. It also greatly enhances the overall strength of the felt unit and the rigid insulation felt, effectively improving the phenomenon of easy shedding on the surface of soft felt. There is no need to use graphite paper or carbon cloth on the surface of the felt unit, simplifying the preparation process and extending the service life of the rigid graphite felt. In addition, the felt unit can be corona treated before bonding to form activated functional groups on the surface of the felt unit, improving the bonding force between the multilayer felt units, avoiding delamination, and further extending the service life of the rigid graphite felt.

[0041] The technical solution of this application is described in detail below. Please refer to the appendix to the specification. Figure 1 The preparation method includes:

[0042] This application provides a method for preparing rigid thermal insulation felt, including:

[0043] S1, The impregnation composition is applied to the carbon fiber felt to obtain the impregnated felt body; the impregnation composition includes silica, which adheres to the carbon fiber felt during the impregnation process;

[0044] S2, the impregnated felt body is subjected to carbonization and graphitization treatment so that the silica in the impregnated felt body reacts with the carbon fibers in the carbon fiber felt to generate silicon carbide, thereby obtaining the felt body unit.

[0045] S3, multiple felt units are bonded together with an adhesive to obtain the rigid thermal insulation felt.

[0046] Specifically, the carbon fiber felt used in step S1 is a felt made of carbon fiber. Carbon fiber is a special fiber composed of carbon elements, with a carbon content of over 90%. It has high strength and high modulus. Compared with other fiber materials, carbon fiber has low density, high specific strength and specific modulus, and excellent properties such as high temperature resistance, friction resistance, electrical conductivity, thermal conductivity and corrosion resistance. It can improve the thermal insulation performance and strength of carbon fiber felt and rigid insulation felt, and extend the service life of rigid insulation felt.

[0047] Optionally, the carbon fiber felt includes graphite felt, which has good stability and good high temperature resistance; further, the graphite felt includes one or more of viscose-based graphite felt, pitch-based graphite felt, and polyacrylonitrile-based graphite felt (PAN-based graphite felt), which has good thermal insulation performance, high strength, and good durability.

[0048] Specifically, the thickness of the carbon fiber felt used in step S1 is 5-15 mm; understandably, this thickness can be any value within the range of 5-15 mm, for example, the thickness can be 5 mm, 7 mm, 9 mm, 10 mm, 12 mm, 13 mm, 15 mm, etc.; within this thickness range, the silica in the impregnation composition can quickly adhere to the carbon fiber felt, with high adhesion efficiency and good uniformity of the adhesion depth of the silica in the carbon fiber felt, which is beneficial to uniformly improve the strength and thermal insulation performance of the felt unit in subsequent steps, and avoid local performance defects in the obtained rigid thermal insulation felt that lead to a shortened overall service life.

[0049] Silica is a general term for white powdery X-ray amorphous silica and silicates. The main component of silica is silicon dioxide, which mainly refers to precipitated silica, fumed silica, and ultrafine silica gel, and also includes powdered synthetic aluminum silicate and calcium silicate. Silica is a porous material with strong adhesion, tear resistance, and heat and aging resistance. In this embodiment, the silica has a small particle size, high surface reactivity, and is easy to disperse evenly. It can react with carbon fibers in carbon fiber felt at high temperatures to generate silicon carbide, effectively improving the structural strength of rigid insulation felt and extending its service life.

[0050] Specifically, the silica used in the preparation of the impregnation composition has a particle size of 4–20 μm; understandably, this particle size can be any value within 4–20 μm, for example, the thickness can be 4 μm, 5 μm, 7 μm, 10 μm, 12 μm, 15 μm, 17 μm, 20 μm, etc.; within this particle size range, silica can effectively adhere to the carbon fiber felt, and can also efficiently penetrate the voids on the surface or inside of the carbon fiber felt, thereby uniformly adhering to the surface and inside of the carbon fiber felt, improving the adhesion uniformity, and also facilitating the capture of silica by the carbon fibers in the carbon fiber felt, locking the silica in the carbon fiber felt, and improving the adhesion rate and adhesion stability of silica.

[0051] Specifically, the mass fraction of silica in the impregnation composition is 1-5%; it is understood that the mass fraction can be any value from 1 to 5%, for example, the mass fraction can be 1%, 2%, 3%, 3.5%, 4%, 5%, etc.; the impregnation composition is a suspension, and within this mass fraction range, silica can be effectively dispersed, with good dispersion uniformity, convenient and fast adhesion, and can provide a sufficient amount of silica to adhere to the carbon fiber felt, effectively improving the strength of the felt unit and the rigid thermal insulation felt.

[0052] Specifically, the impregnation composition further includes a resin impregnation solution, in which silica is added to form an impregnation suspension. During adhesion, the resin impregnation solution carries the silica to adhere to the carbon fiber felt. The resin impregnation solution includes resin, ethanol, and a thickener. The resin is used to carry the silica to adhere to the carbon fiber filaments when the impregnation composition is applied to the carbon fiber felt, and after drying, the resin in the thickener can harden the carbon fiber felt. The ethanol is anhydrous ethanol, which is used to dilute the resin. The thickener is used to further adjust the viscosity of the resin impregnation solution, increasing the viscosity of the resin impregnation solution, so that the silica in the impregnation composition can have a certain fluidity, making it easier to disperse into the surface of the carbon fiber felt, and also have a certain adhesiveness, firmly adhering to the carbon fiber felt.

[0053] Optionally, the resin includes one or more mixtures of phenolic resin, epoxy resin, acrylic resin, and epoxy polyurethane.

[0054] Optionally, the thickener includes one or more of polyvinyl alcohol fiber, carboxymethyl cellulose fiber, seaweed fiber, hydroxyethyl cellulose, methyl hydroxyethyl cellulose, ethyl hydroxyethyl cellulose and methyl hydroxypropyl cellulose.

[0055] Optionally, the mass ratio of resin to ethanol is 1:(5-15); it is understood that the mass ratio can be any value in the range of 1:(5-15), for example, the mass ratio can be 1:5, 1:8, 1:10, 1:12, 1:13, 1:15, etc.; within this mass ratio range, the resin can be effectively diluted, thereby improving the uniformity of subsequent silica adhesion.

[0056] Optionally, the mass fraction of the thickener in the resin impregnation solution is 1-5%; it is understood that the mass fraction can be any value from 1 to 5%, for example, the mass fraction can be 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5%, etc.; within this mass fraction range, the impregnation composition can have a certain fluidity and adhesion, so that during the impregnation process, the silica can adhere to the carbon fiber felt with the resin, the adhesion is uniform, and it is not easy to drip, thus reducing raw material waste.

[0057] Specifically, in some embodiments, step S1 specifically includes:

[0058] The impregnation composition is added to the carbon fiber felt multiple times by injection to obtain the impregnated felt body; the dosage of the impregnation composition added each time is 1-3 mL / cm. 3 The impregnation composition is added 3 to 8 times.

[0059] In this process, the impregnation composition is injected into the interior of the carbon fiber felt during multiple injections in small amounts to improve the uniformity and reliability of silica adhesion while avoiding material waste. Furthermore, the injection location of the impregnation composition can be the same or different each time to further enhance the uniformity of silica adhesion. Understandably, the dosage of the impregnation composition added each time can be 1–3 mL / cm². 3 Any point value in the array can be added 3 to 8 times, and will not be enumerated here.

[0060] Specifically, in one optional embodiment, the impregnated felt body undergoing carbonization and graphitization treatment is a shaped impregnated felt body, such as... Figure 2 As shown, prior to step S2, the method further includes:

[0061] S201, the impregnated felt is subjected to a shaping treatment at a pressure of 1-5 MPa and a temperature of 150-300°C to obtain the shaped impregnated felt.

[0062] Understandably, the pressure of the shaping process can be any value between 1 and 5 MPa. For example, the pressure can be 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, etc. In addition, the temperature of the shaping process can be any value between 150 and 300°C. For example, the temperature can be 150°C, 200°C, 250°C, 300°C, etc. In this step, the impregnated felt can be effectively shaped and cured, the hardness of the impregnated felt can be increased, the deformation of the impregnated felt can be prevented, and the surface debris of the impregnated felt can also be avoided.

[0063] Specifically, such as Figure 3 As shown, prior to step S2, the method further includes:

[0064] S301, a sealing agent is applied to the surface of the impregnated felt to form a sealing layer on the surface of the impregnated felt, thereby obtaining a sealed impregnated felt; the sealing agent includes resin, ethanol and thickener, the mass ratio of the resin to the ethanol is (1-5):1, and the mass fraction of the thickener in the sealing agent is 5-12%.

[0065] Furthermore, this step is performed before the shaping treatment of the impregnated felt body. That is, after obtaining the impregnated felt body in step S1, the impregnated felt body is air-dried or oven-dried. First, a sealing agent is applied to the surface of the impregnated felt body to obtain a sealed impregnated felt body. Then, the impregnated felt body is shaped to obtain a shaped impregnated felt body. Finally, the shaped impregnated felt body is carbonized and graphitized to obtain a felt body unit.

[0066] Optionally, the resin in the sealant is one or a mixture of phenolic resin, epoxy resin, acrylic resin and epoxy polyurethane; optionally, the thickener is one or a mixture of polyvinyl alcohol fiber, carboxymethyl cellulose fiber, seaweed fiber, hydroxyethyl cellulose, methyl hydroxyethyl cellulose, ethyl hydroxyethyl cellulose and methyl hydroxypropyl cellulose.

[0067] Understandably, the mass ratio of resin to ethanol in the sealant can be any value from (1 to 5):1. For example, the mass ratio can be 1:1, 2:1, 3:1, 4:1, 5:1, etc. Within this mass ratio range, the resin can be effectively diluted, improving the uniformity of resin dispersion in the sealant. At the same time, the resin concentration in the sealant is relatively large, which is beneficial to further enhance the interlayer adhesion.

[0068] Understandably, the mass fraction of the thickener in the sealant can be any value between 5% and 12%, for example, the mass fraction can be 5%, 6%, 8%, 9%, 10%, 11%, 12%, etc. Within this mass fraction range, the flowability of the sealant can be reduced, the viscosity of the sealant can be increased, and the surface porosity can be reduced, so that the sealant can stably form a film on the surface of the impregnated felt, effectively sealing the surface of the impregnated felt, preventing the impregnated felt from flaking off in subsequent preparation processes, especially preventing the precipitated silica from falling off, improving the effectiveness of subsequent steps in improving the strength and thermal insulation performance of the impregnated felt, and ensuring good preparation stability.

[0069] This step, specifically applying a sealing agent to the surface of the impregnated felt, may include:

[0070] A sealing agent is applied multiple times to the surface of the impregnated felt with precipitated silica to form a sealing layer of a predetermined thickness on the surface of the impregnated felt, resulting in a sealed impregnated felt.

[0071] The preset thickness of the sealing layer can be controlled through multiple coatings. The final preset thickness of the sealing layer is 0.01 to 0.05 mm. Understandably, the preset thickness can be any value within the range of 0.01 to 0.05 mm. For example, the preset thickness is 0.01 mm, 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, etc. Within this preset thickness range, a dense sealing layer can be formed, effectively sealing the impregnated felt, reducing the risk of surface debris shedding, improving the reliability of the subsequent reaction between silica and cellulose to generate silicon carbide, and making the surface hardness of the impregnated felt higher than that of the interior, thus enhancing the surface strength of the impregnated felt, improving the phenomenon of easy shedding of carbon fiber felt, eliminating the need for the process of pasting graphite paper or carbon cloth on the surface, greatly simplifying the preparation process and improving the convenience of preparation.

[0072] Specifically, in step S2, carbonization is a heat treatment method. Under high temperature and vacuum conditions, the resin adhering to the surface of the impregnated carbon fiber undergoes a carbonization reaction to generate resin carbon. Combined with subsequent graphitization treatment, it can enhance the strength of the carbon fiber and the felt unit without increasing the density of the felt unit, thus effectively maintaining the thermal insulation performance of the felt unit and the final product, rigid thermal insulation felt.

[0073] In some optional embodiments, the carbonization temperature is 800–1100°C, and the carbonization time is 4–8 hours. Understandably, the temperature can be any value within the range of 800–1100°C, and the time can be any value within the range of 4–8 hours. For example, the temperature can be 800°C, 850°C, 900°C, 1000°C, 1050°C, 1100°C, etc., and the time can be 4 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 8 hours, etc. Within this temperature and time range, the internally attached resin can stably undergo a carbonization reaction, resulting in a highly efficient reaction and facilitating the subsequent graphitization reaction.

[0074] Specifically, graphitization treatment involves heat-treating the impregnated felt at high temperatures, causing the silica to react with the carbon fibers or surrounding resin carbon to generate silicon carbide. This effectively increases the strength of the felt unit without altering its main structure. It also removes impurities, improves purity, corrects surface defects in the carbon fibers, increases surface hardness and wear resistance, enhances oxidation and corrosion resistance, reduces the coefficient of thermal expansion, and minimizes surface wear and fatigue cracks. This significantly improves the mechanical properties, chemical stability, and durability of the carbon fibers and the felt unit.

[0075] In some optional embodiments, the graphitization treatment temperature is 2000–2200°C, and the graphitization treatment time is 10–15 hours. Understandably, the temperature can be any value within the range of 2000–2200°C, and the time can be any value within the range of 10–15 hours. For example, the temperature can be 2000°C, 2030°C, 2050°C, 2100°C, 2150°C, 2200°C, etc., and the time can be 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 14.5 hours, 15 hours, etc. Within this temperature and time range, impurities can be effectively eliminated, purity can be improved, thereby enhancing wear resistance and chemical stability, and the overall strength and durability of the felt unit are further improved.

[0076] Through the carbonization and graphitization processes in step S2, high-strength felt units are prepared, significantly enhancing the overall strength of the felt units and rigid insulation felt. Furthermore, the amount of silica adhering to the carbon fibers is minimal, allowing it to react entirely to form silicon carbide. The small amount of silica does not reduce the porosity of the felt units, thus preserving their main structure and original pore structure, and does not increase their density. This effectively maintains the insulation performance of the felt units and rigid insulation felt. Simultaneously, it improves the problem of easy shedding of carbon fiber felt surfaces, eliminating the need for graphite paper or carbon cloth to be pasted on the surface. This simplifies the preparation process of rigid insulation felt, reducing preparation difficulty and facilitating large-scale mass production.

[0077] Specifically, the felt units in the process of bonding multiple felt units together with an adhesive are activated felt units, such as... Figure 4 As shown, prior to step S3, the method further includes:

[0078] S401, the surface of the felt unit is subjected to corona treatment to form activated functional groups on the surface of the felt unit, thereby obtaining an activated felt unit; the power of the corona treatment is 10-30kW, and the corona treatment time is 15-100s; during the bonding process, the activated functional groups can be connected to the adhesive through chemical bonds.

[0079] Corona treatment is an electrostatic treatment used to modify the surface of the felt unit. This process causes the carbon fiber molecules on the felt unit surface to break chemical bonds and degrade. Simultaneously, the discharge process oxidizes the carbon fibers on the felt unit surface, generating highly polar activated functional groups such as carbonyl groups and peroxides. This increases the surface energy of the felt unit, significantly enhancing its adhesion. These activated functional groups can chemically bond with the adhesive, improving the interlayer bonding strength between multiple activated felt units during subsequent bonding. This increases the interlayer tightness of the rigid insulation felt, making it less prone to cracking. It solves the problems of poor bonding strength and easy delamination during use, and also improves the strength and extends the service life of the rigid insulation felt.

[0080] Understandably, the power of the corona treatment can be any value between 10 and 30 kW, and the corona treatment time can be any value between 15 and 100 s. For example, the power can be 10 kW, 15 kW, 18 kW, 20 kW, 25 kW, 30 kW, etc., and the time can be 15 s, 20 s, 30 s, 50 s, 60 s, 80 s, 90 s, 100 s, etc. Within this power and time range, the activation efficiency is high, and a large number of activated functional groups can be stably formed on the surface of the felt unit. These activated functional groups can chemically react with the adhesive during the subsequent bonding process and bond together. Moreover, the strength of the chemical bond connection is much stronger than that of the physical bond, thereby improving the interlayer shear force of the rigid thermal insulation felt and enhancing the overall performance of the rigid thermal insulation felt.

[0081] Specifically, in some alternative embodiments, after obtaining the felt unit in step S2 and before corona treatment of the surface of the felt unit, the method further includes:

[0082] The felt unit was ultrasonically cleaned in anhydrous ethanol and dried to obtain the cleaned felt unit.

[0083] In this step, the cleaned felt unit is used for corona treatment. That is, the felt unit in the corona treatment step is the cleaned felt unit. On the one hand, this avoids the surface stains of the felt unit from affecting the effectiveness of subsequent steps. On the other hand, it helps to improve the activation efficiency and activation degree of the corona treatment, so as to facilitate the formation of a large number of activated functional groups and improve the activation reliability.

[0084] Specifically, in step S3, an adhesive is coated onto the activated felt unit, and the side of the activated felt unit with the adhesive is bonded. This allows the adhesive and the activated functional groups to form interlayer connections through chemical bonds during the bonding process, greatly improving the interlayer bonding force and effectively preventing delamination. The adhesive includes resin and ethanol, and the adhesive is obtained by diluting the resin with ethanol. The mass ratio of the resin to ethanol is 1:(3-10). Understandably, this mass ratio can be any value within 1:(3-10), for example, 1:3, 1:4, 1:5, 1:7, 1:9, 1:10, etc. Within this mass ratio range, the adhesive has good adhesion, which is conducive to the effective components in the adhesive fully contacting and reacting with the activated functional groups, effectively bonding two adjacent activated felt units.

[0085] In some alternative embodiments, the adhesive can be sprayed onto the surface of the activated felt unit by atomization spraying. This is beneficial for the adhesive to fully contact and react with the activated functional groups to form chemical bonds. It also helps to improve the uniformity of the adhesive distribution on the surface of the activated felt unit, thereby improving the bonding uniformity and bonding strength. This avoids local delamination of the rigid insulation felt due to weak local bonding strength, which would affect the overall strength and service life of the rigid insulation felt.

[0086] Specifically, among two adjacent activated felt units, at least one of the activated felt units can be coated with adhesive for bonding; alternatively, both of the surfaces of the two adjacent activated felt units can be coated with adhesive, and the adhesive-coated sides of the two activated felt units can be bonded together; preferably, any one of the two adjacent activated felt units can be coated with adhesive, while the other activated felt unit does not need to be coated with adhesive, and the adhesive-coated side of the activated felt unit is bonded to the other activated felt unit, so that the adhesive can chemically react with the activated functional groups on the surface of the other activated felt unit to form chemical bonds, and the chemical bonding replaces the original simple physical bonding, effectively strengthening the interlayer bonding strength.

[0087] Specifically, in some optional embodiments, the thickness of the adhesive coating formed by applying the adhesive to the activated felt unit is 0.001 to 0.01 mm; it is understood that the thickness can be any value from 0.001 to 0.01 mm, for example, the thickness can be 0.001 mm, 0.003 mm, 0.005 mm, 0.007 mm, 0.01 mm, etc.; within this thickness range, a sufficient amount of adhesive can be provided to react with the activated functional groups in the activated felt unit, and a sufficient amount of adhesive can also be provided to react with the activated functional groups in an adjacent activated felt unit, which greatly improves the interlayer bonding force of the rigid insulation felt, enhances the overall strength of the rigid insulation felt, extends the service life of the rigid insulation felt, and also avoids the waste of raw materials and the impact on the performance of the rigid insulation felt caused by excessive thickness.

[0088] Compared to existing technologies that rely solely on adhesives for bonding rigid insulation felt, this method, which involves corona treatment followed by adhesive bonding, allows for interlayer bonding between activated felt units through chemical bonds, replacing the physical bonding of the adhesive. This results in stronger interlayer bonding and reduces the likelihood of cracking. Furthermore, compared to some existing methods that address delamination through needle punching, this method is simpler, less difficult to manufacture, and unaffected by the thickness of the rigid insulation felt. It solves the delamination problem of traditional rigid insulation felt while simplifying the manufacturing process. Moreover, the corona treatment followed by bonding, combined with the silicon carbide generated from the reaction of silica and carbon fiber, makes the rigid insulation felt more resistant to corrosion, exhibits excellent high-temperature resistance, and extends its lifespan by over 80%, reaching 18-24 months. This reduces the frequency of replacement and lowers user maintenance costs.

[0089] Specifically, after bonding the plurality of felt units together with an adhesive, the method further includes:

[0090] The multiple activated felt units that have been bonded together are hot-pressed at a temperature of 150–300°C to obtain the rigid thermal insulation felt.

[0091] The thickness of the rigid insulation felt can be adjusted by the number of layers of the bonded felt units; the heating and curing by hot pressing can promote interlayer bonding between the multiple activated felt units after bonding, promoting chemical bond connection. Hot pressing can also further control the thickness of the rigid insulation felt, so that the thickness of the rigid insulation felt is within the desired thickness range; optionally, the desired thickness is 3 to 5 cm, and the thickness adjustment of the rigid insulation felt is relatively flexible and highly operable.

[0092] The hot-pressing pressure is 1–5 MPa; understandably, the hot-pressing pressure can be any value within 1–5 MPa, for example, the pressure can be 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, etc.; in addition, the hot-pressing temperature can be any value within 150–300℃, for example, the temperature can be 150℃, 200℃, 250℃, 300℃, etc.; the hot-pressing effect is good, which can solidify the rigid insulation felt firmly, improve the bonding reliability, avoid delamination, and at the same time, the rigid insulation felt has high forming precision, which can effectively control the thickness within the desired thickness.

[0093] In some alternative embodiments, a second coating of polycarbosilane is applied to the surface of the hot-pressed rigid insulation felt, which helps to improve the surface hardness and also enhances the oxidation resistance and corrosion resistance of the rigid insulation felt.

[0094] Preferably, in some embodiments, after hot pressing, the hot-pressed rigid insulation felt is subjected to carbonization and graphitization treatments again. The carbonization temperature is 800–1100℃, and the graphitization temperature is 2000–2200℃, to obtain a rigid insulation felt. Thus, overall graphitization after bonding and hot pressing is beneficial for further improving the performance of the rigid graphite felt, including a synergistic improvement in various properties such as strength, wear resistance, chemical stability, and thermal insulation performance. This application also provides a rigid insulation felt obtained by the preparation method described in any of the preceding claims. The preparation is simple, and the obtained rigid insulation felt has a compressive strength greater than or equal to 2.17 MPa, an interlaminar shear strength greater than or equal to 15.22 MPa, and a thermal conductivity less than or equal to 0.2 W / m·K. The rigid insulation felt exhibits strong interlaminar bonding, high overall strength, and excellent thermal insulation performance.

[0095] The following describes specific embodiments of this application in conjunction with the above preparation method.

[0096] Example 1

[0097] The impregnation composition is injected into a 1 cm thick PAN-based carbon felt using an injection method, in small, multiple injections, with each injection volume being 1 mL / cm. 3 The impregnation process is repeated 8 times to obtain an impregnated felt body. The impregnation composition is prepared by adding silica to a resin impregnation solution. The silica has a particle size of less than or equal to 15 μm and a mass fraction of 2%. The resin impregnation solution includes ethanol and phenolic resin in a mass ratio of 5:1, and also includes methyl hydroxyethyl cellulose with a mass fraction of 1%.

[0098] The impregnated felt is air-dried naturally. A sealing agent (ethanol resin mass ratio of 1:3 and thickener mass fraction of 5%) is applied to the surface of the air-dried impregnated felt to seal the surface. The coating thickness is 0.03 mm, resulting in the sealed impregnated felt.

[0099] The sealed impregnated felt is then subjected to a shaping treatment at a pressure of 2 MPa and a temperature of 200℃ to obtain the shaped impregnated felt.

[0100] The shaped felt body was heated to 1000℃ at a constant temperature of 50℃ / h, carbonized for 4 hours, and then graphitized at 2000℃ for 10 hours to obtain the felt body unit.

[0101] The felt unit was ultrasonically washed in anhydrous ethanol and then air-dried to obtain the cleaned felt unit.

[0102] The cleaned felt unit was subjected to corona treatment with a power of 15 kW and a duration of 20 seconds to obtain an activated felt unit.

[0103] The adhesive is sprayed onto the surface of the activated felt unit by atomization spraying, and the coating thickness is 0.003 mm; wherein the adhesive includes epoxy resin and ethanol in a mass ratio of 1:3.

[0104] The felt units coated with adhesive were bonded together and then hot-pressed and cured at 220°C and 2MPa for 4 hours, carbonized at 900°C for 5 hours, and graphitized at 2000°C for 10 hours to obtain a rigid thermal insulation felt with a thickness of 4 cm.

[0105] Example 2

[0106] The impregnation composition is injected into a 1 cm thick PAN-based carbon felt using an injection method, in small, multiple injections, with each injection volume being 3 mL / cm. 3 The impregnation process is repeated three times to obtain an impregnated felt body. The impregnation composition is prepared by adding silica to a resin impregnation solution. The silica has a particle size of less than or equal to 5 μm and a mass fraction of 3%. The resin impregnation solution includes ethanol and phenolic resin in a mass ratio of 15:1, and also includes methyl hydroxyethyl cellulose with a mass fraction of 3%.

[0107] The impregnated felt is air-dried naturally. A sealing agent (ethanol resin mass ratio of 1:1 and thickener mass fraction of 10%) is applied to the surface of the air-dried impregnated felt to seal the surface. The coating thickness is 0.01 mm to obtain the sealed impregnated felt.

[0108] The sealed impregnated felt is then subjected to a shaping treatment at a pressure of 1 MPa and a temperature of 200℃ to obtain the shaped impregnated felt.

[0109] The shaped felt body was heated to 800℃ at a constant temperature of 50℃ / h, carbonized for 5h, and then graphitized at 2000℃ for 15h to obtain the felt body unit.

[0110] The felt unit was ultrasonically washed in anhydrous ethanol and then air-dried to obtain the cleaned felt unit.

[0111] The cleaned felt unit was subjected to corona treatment with a power of 20 kW and a duration of 30 s to obtain an activated felt unit.

[0112] The adhesive is sprayed onto the surface of the activated felt unit by atomization spraying, and the coating thickness is 0.005 mm; wherein the adhesive includes epoxy resin and ethanol in a mass ratio of 1:5.

[0113] The felt units coated with adhesive were bonded together and then hot-pressed and cured at 220°C and 2MPa for 4 hours, carbonized at 900°C for 5 hours, and graphitized at 2000°C for 10 hours to obtain a rigid thermal insulation felt with a thickness of 4 cm.

[0114] Example 3

[0115] The impregnation composition is injected into a 1 cm thick PAN-based carbon felt using an injection method, in small, multiple injections, with each injection volume being 2 mL / cm. 3 The impregnation process is repeated 5 times to obtain an impregnated felt body. The impregnation composition is prepared by adding silica to a resin impregnation solution. The silica has a particle size of less than or equal to 20 μm and a mass fraction of 5%. The resin impregnation solution includes ethanol and phenolic resin in a mass ratio of 10:1, and also includes methyl hydroxyethyl cellulose with a mass fraction of 5%.

[0116] The impregnated felt is air-dried naturally. A sealing agent (ethanol resin mass ratio of 1:5 and thickener mass fraction of 8%) is applied to the surface of the air-dried impregnated felt to seal the surface. The coating thickness is 0.05 mm to obtain the sealed impregnated felt.

[0117] The sealed impregnated felt is then subjected to a shaping treatment at a pressure of 4 MPa and a temperature of 200℃ to obtain the shaped impregnated felt.

[0118] The shaped felt body was heated to 1100℃ at a constant temperature of 50℃ / h, carbonized for 4 hours, and then graphitized at 2000℃ for 10 hours to obtain the felt body unit.

[0119] The felt unit was ultrasonically washed in anhydrous ethanol and then air-dried to obtain the cleaned felt unit.

[0120] The cleaned felt unit was subjected to corona treatment with a power of 30 kW and a duration of 50 s to obtain an activated felt unit.

[0121] The adhesive is sprayed onto the surface of the activated felt unit by atomization spraying, and the coating thickness is 0.008 mm; wherein the adhesive includes epoxy resin and ethanol in a mass ratio of 1:10.

[0122] The felt units coated with adhesive were bonded together and then hot-pressed and cured at 220°C and 2MPa for 4 hours, carbonized at 900°C for 5 hours, and graphitized at 2000°C for 10 hours to obtain a rigid thermal insulation felt with a thickness of 4 cm.

[0123] Example 4

[0124] The impregnation composition is injected into a 1 cm thick pitch-based carbon felt using an injection method, in small, multiple injections, with each injection being 1 mL / cm. 3 The impregnation process is repeated 8 times to obtain an impregnated felt body. The impregnation composition is prepared by adding silica to a resin impregnation solution. The silica has a particle size of less than or equal to 20 μm and a mass fraction of 4%. The resin impregnation solution includes ethanol and phenolic resin in a mass ratio of 8:1, and also includes methyl hydroxyethyl cellulose with a mass fraction of 4%.

[0125] The impregnated felt is air-dried naturally. A sealing agent (ethanol resin mass ratio of 1:4 and thickener mass fraction of 7%) is applied to the surface of the air-dried impregnated felt to seal the surface. The coating thickness is 0.04 mm, resulting in the sealed impregnated felt.

[0126] The sealed impregnated felt is then subjected to a shaping treatment at a pressure of 4 MPa and a temperature of 200℃ to obtain the shaped impregnated felt.

[0127] The shaped felt body was heated to 900℃ at a constant temperature of 50℃ / h, carbonized for 4 hours, and then graphitized at 2000℃ for 10 hours to obtain the felt body unit.

[0128] The felt unit was ultrasonically washed in anhydrous ethanol and then air-dried to obtain the cleaned felt unit.

[0129] The cleaned felt unit was subjected to corona treatment with a power of 25 kW and a duration of 60 s to obtain an activated felt unit.

[0130] The adhesive is sprayed onto the surface of the activated felt unit by atomization spraying, and the coating thickness is 0.006 mm; wherein the adhesive includes epoxy resin and ethanol in a mass ratio of 1:9.

[0131] The felt units coated with adhesive were bonded together and then hot-pressed and cured at 220°C and 2MPa for 4 hours, carbonized at 900°C for 5 hours, and graphitized at 2000°C for 10 hours to obtain a rigid thermal insulation felt with a thickness of 4 cm.

[0132] Comparative Example

[0133] The impregnation composition is injected into a 1 cm thick PAN-based carbon felt using an injection method, in small, multiple injections, with each injection volume being 3 mL / cm. 3The impregnation process is repeated three times to obtain an impregnated felt body. The impregnation composition is prepared by adding silica to a resin impregnation solution. The silica has a particle size of less than or equal to 10 μm and a mass fraction of 1%. The resin impregnation solution includes ethanol and phenolic resin in a mass ratio of 10:1, and also includes methyl hydroxyethyl cellulose with a mass fraction of 2%.

[0134] The impregnated felt is air-dried naturally. A sealing agent (ethanol resin mass ratio of 1:2 and thickener mass fraction of 6%) is applied to the surface of the air-dried impregnated felt to seal the surface. The coating thickness is 0.02 mm to obtain the sealed impregnated felt.

[0135] The sealed impregnated felt is then subjected to a shaping treatment at a pressure of 3 MPa and a temperature of 200℃ to obtain the shaped impregnated felt.

[0136] The shaped felt body was heated to 900℃ at a constant temperature of 50℃ / h, carbonized for 5h, and then graphitized at 2000℃ for 15h to obtain the felt body unit.

[0137] The felt unit was ultrasonically washed in anhydrous ethanol and then air-dried to obtain the cleaned felt unit.

[0138] The adhesive is sprayed onto the surface of the cleaned felt unit by atomization spraying, and the coating thickness is 0.002mm; wherein the adhesive consists of resin and ethanol in a mass ratio of 1:3.

[0139] The felt units coated with adhesive were bonded together and then hot-pressed and cured at 220°C and 2MPa for 4 hours, carbonized at 900°C for 5 hours, and graphitized at 2000°C for 10 hours to obtain a rigid thermal insulation felt with a thickness of 4 cm.

[0140] The rigid thermal insulation felts prepared in Examples 1-4 and the comparative example without corona treatment were subjected to performance tests. The test results are shown in Table 1 below. It can be seen that the rigid thermal insulation felt prepared by this method has a compressive strength greater than or equal to 2.17 MPa, an interlaminar shear strength greater than or equal to 15.22 MPa, and a thermal conductivity less than or equal to 0.2 W / m·K, and has high strength, strong interlaminar bonding force and excellent thermal insulation performance.

[0141] Table 1 Test results of Examples 1-4 and Comparative Examples

[0142]

[0143]

[0144] The above description is merely some embodiments of this application and is not intended to limit this application. Those skilled in the art should understand that various changes and improvements may be made to this application, and any modifications, equivalent substitutions and improvements made in accordance with this application fall within the scope of protection claimed by this application.

Claims

1. A method for preparing a rigid thermal insulation felt, characterized in that, include: S1, The impregnation composition is applied to the carbon fiber felt to obtain the impregnated felt body; the impregnation composition includes silica, which adheres to the carbon fiber felt during the impregnation process; S2, the impregnated felt body is subjected to carbonization and graphitization treatment so that the silica in the impregnated felt body reacts with the carbon fibers in the carbon fiber felt to generate silicon carbide, thereby obtaining the felt body unit. The surface of the felt unit is subjected to corona treatment to form activated functional groups on the surface of the felt unit, thereby obtaining an activated felt unit; the power of the corona treatment is 10 to 30 kW, and the corona treatment time is 15 to 100 s; S3, multiple felt units are bonded together using an adhesive to obtain the rigid thermal insulation felt; the adhesive includes resin and ethanol, and during the bonding process, the activated functional groups can be chemically bonded to the adhesive; the rigid thermal insulation felt has a compressive strength greater than or equal to 2.17 MPa, an interlaminar shear strength greater than or equal to 15.22 MPa, and a thermal conductivity less than or equal to 0.2 W / m·K.

2. The preparation method according to claim 1, characterized in that, The impregnated felt body undergoing carbonization and graphitization treatment is a shaped impregnated felt body. Before step S2, the method further includes: The impregnated felt is subjected to a shaping treatment at a pressure of 1-5 MPa and a temperature of 150-300°C to obtain a shaped impregnated felt.

3. The preparation method according to claim 1, characterized in that, The carbonization treatment temperature is 800–1100℃, and the carbonization treatment time is 4–8 hours; The graphitization treatment temperature is 2000–2200℃, and the carbonization treatment time is 10–15 h.

4. The preparation method according to claim 1, characterized in that, After bonding the plurality of felt units together with an adhesive, the method further includes: The bonded activated felt units are hot-pressed at a temperature of 150–300°C to obtain the rigid thermal insulation felt.

5. The preparation method according to any one of claims 1-4, characterized in that, The carbon fiber felt includes graphite felt, which includes one or more of the following: viscose-based graphite felt, pitch-based graphite felt, and polyacrylonitrile-based graphite felt.

6. The preparation method according to any one of claims 1-4, characterized in that, The impregnation composition satisfies at least one of the following characteristics: The particle size of the silica is 4–20 μm; The mass fraction of the silica in the impregnation composition is 1-5%; The impregnation composition further includes a resin impregnation solution comprising resin, ethanol and a thickener, wherein the mass ratio of the resin to the ethanol is 1:(5-15), and the mass fraction of the thickener in the resin impregnation solution is 1-5%. The resin includes one or more of phenolic resin, epoxy resin, acrylic resin and epoxy polyurethane; The thickener includes one or more of polyvinyl alcohol fiber, carboxymethyl cellulose fiber, seaweed fiber, hydroxyethyl cellulose, methyl hydroxyethyl cellulose, ethyl hydroxyethyl cellulose and methyl hydroxypropyl cellulose.

7. The preparation method according to any one of claims 1-4, characterized in that, Step S1 includes: The impregnation composition is added to the carbon fiber felt multiple times by injection to obtain the impregnated felt body; the thickness of the carbon fiber felt is 5-15 mm, and the dosage of the impregnation composition added each time is 1-3 mL / cm. 3 The impregnation composition is added 3 to 8 times.

8. The preparation method according to any one of claims 1-4, characterized in that, Prior to step S2, the method further includes: A sealing agent is applied to the surface of the impregnated felt to form a sealing layer on the surface of the impregnated felt, thereby obtaining a sealed impregnated felt; the sealing agent includes resin, ethanol and thickener, wherein the mass ratio of resin to ethanol is (1-5):1, and the mass fraction of thickener in the sealing agent is 5-12%.

9. A rigid thermal insulation felt, characterized in that, The rigid thermal insulation felt is obtained by the preparation method according to any one of claims 1-8.

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